The World Health Organization (WHO) listed the nOPV2 vaccine for emergency use to address the outbreak of type 2 circulating vaccine-derived poliovirus (cVDPV2). This is the first emergency use listing (EUL) of a vaccine which may be granted for future coronavirus vaccines.
In the global effort to eradicate polio since the late 1980s, companies developed the oral polio vaccine (OPV). As a result, wild polio cases dropped by 99% and saved millions of children from paralysis.
Eradicating Polio
However, communities that do not have enough immunized individuals allow the weakened virus in the OPV to circulate and evolve back to the original virus that causes polio, known as type 2 circulating vaccine-derived poliovirus. Despite switching to another version of the OPV, there were still several outbreaks in Africa, the Mediterranean, Southeast Asia, and the Western Pacific.
Virologist Vincent Racaniello from Columbia University explained that when nOPV strains were previously tested in a few volunteers, it did not genetically revert to the polio-causing form. However, rare events of polio endemics occur "when they are used for mass immunization of millions."
The recent efforts are part of the Global Polio Eradication Initiative's Polio Endgame Strategy 2019-2023. Moreover, responses to multiple outbreaks such as house-to-house campaigns are on hold due to the current coronavirus pandemic. The EUL of the nOPV2 vaccine is also a response to UNICEF's and the WHO's urgent call to action in dealing with ongoing measles and polio epidemics.
New Polio Vaccine
The vaccine is manufactured by BioFarma and technical development was done by a group of consortium members. The program was coordinated and managed by PATH. Batavia Biosciences was involved in testing the feasibility of an alternative cost-effective manufacturing platform.
A study published in the journal Cell Host & Microbe earlier this year describes the development of the nOPV2 vaccine which is "genetically more stable and less likely to regain virulence than the original Sabin2 strain," wrote the researchers. Phase 1 of clinical trials with 15 volunteers resulted in a robust antibody response to the virus.
The EUL also includes the analysis of phases two and three clinical trials to determine the efficacy of the new vaccine and ensure manufacturing quality. Countries will then get to decide if they will use the vaccine and prepare for the implementation of the new polio vaccine. For full licensure and prequalification of the nOPV2 vaccine, Batavia Biosciences has committed to continuously generate data.
Experts believe that the EUL for the vaccine will also be applicable for Covid-19 vaccines in the near future. However, Raul Andino from the University of California - San Francisco believes that the fight against polio teaches us "that it will take time to develop an optimal vaccine against SARS-CoV-2, and early efforts are likely to meet with unexpected challenges."
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